Fibonacci numbers are practically unheard of outside of math circles, and yet the math, science, and even art concepts that tie into them are many. Spiral Science & Math Manipulative is an elegant and inexpensive way to extensively explore these relationships.
Ds#1 and I have been trying out the many acitivities available at the web site. Middle school or above students with a good understanding of fractions, decimals, and percentages will get the most out of this neat kit, though upper elementary kids can use it for simpler activities. Ds#1 does not have that much math under his belt, but enjoyed the activity on hand bone ratios nonetheless. He was able to figure out the pattern of the Fibonacci sequence after a bit of thought--and that made it all the more wonderful for him.
The 13x21 cm kit consists of 7 magnetic sheets that have numbers and a spiral-forming curve on one side and examples of spirals in nature on the other, a magnetic sheet to work on, and a thick vinyl pouch to keep it in. The Teacher's Guide is included, containing six lessons, and the web site has another 8 activities all aligned to national standards (if you keep track of them.) You can also buy class packs for your co-op, but these are significantly more expensive.
Some of the vocabulary and concepts you will explore with this kit include logarithmic (Archimedes) spiral, tessellations, ratio, proportion, golden mean, interval scale, X and Y axis, controls and variables, histogram, average, and more. With a cost of less than $15, this kit certainly offers a lot of science and math exploration for the dollar.